When a pad is rotatably driven to act on a floor surface, there occurs a difference in the peripheral speed between the center portion and the outer peripheral portion of the pad. For this reason, even if the pad acts on the floor surface at an appropriate speed in its outer peripheral portion, the pad fails to provide sufficient polishing effect at the center portion thereof. Especially, such insufficient or irregular work would occur more likely when the pad is formed large to provide an increased working area. On the other hand, if the pad is driven to effect a reciprocal movement relative to the floor surface, such pad can act on the floor surface at an equal speed over the entire face thereof. Then, even if this pad is formed large, such insufficient or irregular work will less likely to occur even for the enlarged working area of the pad.
As such apparatus having a pad which is reciprocated relative to the floor surface is known from e.g. Japanese Utility Model “Kokoku” No.: Sho. 35-6288 (referred to as “prior art 1”, hereinafter) and Japanese Patent Application “Kokai” No.: Hei. 7-39506 (referred to as “prior art 2” hereinafter).
The prior art 1 discloses a construction in which each of a pair of pads is supported to be movable along a guide dovetail groove and a small gear is meshed with a large gear coupled with one pad via a rod and with a large gear coupled with the other pad via a rod. A worm gear is meshed with this small gear, so that as a worm member meshed with the worm gear is driven by an electric motor, each large gear is driven, whereby the respective rods are reciprocated by the rotational drive from the large gears, thus reciprocating the respective pads. With this driving technique, the pair of pads are driven to be reciprocated with one pad being advanced and the other being retracted along a direction normal to the juxtaposing direction of the pads. For this reason, there would tend to generate a reaction force from the floor surface which force tends to causes rotational displacement of the apparatus frame. Also, since the power transmission is effected by means of meshing of the gears, a large drive noise would be generated.
The prior art 2 discloses a construction in which each of a pair of pads is coupled to a mount frame via two anti-vibration rubber elements and to one ends of these anti-vibration rubber elements, vibration plates are connected and the other ends of the vibration plates are attached to an eccentric shaft. As this eccentric shaft is driven by a motor for reciprocating the respective vibration plates, the vibration plates drive and reciprocate the pads via the anti-vibration rubber elements as the pivots. With this driving technique, since the pads are pivoted via the anti-vibration rubber elements as the pivots, there would occur vibrations such as vertical vibrations of the pads. Further, if the moving stroke of the pad is to be increased, this will necessitate increase in the deformation amount at the pivot. However, with such large deformation at the pivot, there will occur resistance against the movement of the pivot due to the load for pressing the pad against the floor surface. As a result, a driving problem or failure would tend to occur. In view of this, it was actually not possible to secure such a large movement stroke for the pad.
Therefore, a primary object of the present invention is to provide an electric-motored floor-surface polisher whose pad can act on the entire floor surface at an equal speed and on a maximum area of the floor surface and which yet can reduce occurrence of a reaction force from the floor surface or vibration of the apparatus frame due to the driving and generation of noise.